Semihosting is a technique to do printf() debugging through an active debug connection. So instead using a physical connection like RS-232 or USB CDC, the connection to the host machine is through the debugger. This post is about enabling and using semihosting with gcc and newlib/newlib-nano in Freescale Eclipse based Kinetis Design Studio (KDS) using the GNU ARM Eclipse plugins.
Semihosting Console View with output
The Freescale FRDM-K64F is a great board for data logger applications: it has a powerful ARM Cortex M4F with 120 MHz, 1 MB Flash and 256 KByte RAM. Best of all: it already has a micro SD card socket on the board :-).
Data Logger with FRDM-K64F
Feeling that building a project in Eclipse (including Kinetis Design Studio) takes a long time? Then probably the ‘parallel build’ option is not enabled in your project: Using parallel build option reduces the needed time by factors. To give an example, to build a project with 56 source files takes 32 seconds without parallel build enabled:
no parallel build
With parallel build enabled this gets reduced down to less than 10 seconds:
Parallel Build Enabled
🙂
For the next semester I will do things differently in my advanced embedded systems programming course (INTRO) at the University of Lucerne: Instead of using the Freescale provided CodeWarrior, we will use a DIY tool chain for ARM with Eclipse Kepler.
Eclipse Kepler Ready for Classroom Usage
That way we we can offer students an open and convenient tool chain for their lab work, course assignments and own projects both at work and at home. So this post is about spending about 30 minutes to build your own tool chain which then can passed to students and coworkers so they have a complete toolchain installed in a few minutes.
For the GNU ARM tools it is easy to print out the code and date size information, see
But this is all for ARM cores. What if I use other architectures like S08 or ColdFire in Eclipse?
Code Size Information in Build Console
The existing OpenSDAv1 (see “OpenSDA on the Freedom KL25Z Board“) bootloader is using the industry standard Motorola S-Record (S19) Files. However, new FRDM-K64F board (see “FTF: FRDM-K64F, Kinetis Design Studio and Kinetis SDK“) has OpenSDAv2 on it, which is an mbed bootloader. So how to create files with an IDE other than mbed for that bootloader which is present on the FRDM-K64F board by default? Well, creating binary files is one thing, but to have it working with the mbed bootloader is another challenge :-(.
FRDM-K64F with mbed MSD bootloader
my students sometimes are afraid to ask questions, although I urge them ask any question. In my opinion there are no ‘dumb’ questions: only questioning things let us think and learn new things. I see that many readers of this blog are *not* afraid to comment or ask questions. The WordPress statistics shows 5’687 questions/comments for this blog (thank you all!), and the spam filter protected me from 202,341 items (ok, these *are* dumb) :-).
The ‘question of the week’ comes from Andy. That question caused me some serious head scratching, but the same time I have learned something important and useful for my next project: how to tell the ARM GNU linker *not* to initialize variables?
GNU ARM Embedded Linker Options
One question I have been asked several times here at FTF:
“How can I create an S19/Motorola S-Record with Eclipse?”
The answer depends on which Eclipse you are using. Actually it depends on which (ARM) build tools plugin you are using, as with Eclipse you have the freedom of choice.
And this is not only about S19/Binary (Flash Image), but covers ‘Extended Listing’ and ‘Print Size’:
Additional Tool Options
FreeRTOS has many memory allocation options (see Memory Management) with four ‘schemes’. One of it is the a simple wrapper over the library malloc() and free() routines. I admit, I have not used them, as usually I avoid to include such kind of libraries, as they have their own problems. Anyway, a discussion in the FreeRTOS forum raised my interest: obviously some malloc() implementation (as in the EWL library of CodeWarrior) are making a safety check against the current stack pointer.
Maybe you had this problem too: you shared a project with somebody, only to realize that your carefully crafted debug configuration was not shared?
Eclipse has the concept to store settings in the ‘framework’. The ‘framework’ is the Eclipse internal data, basically what is inside the .metadata folder of the workspace.
metadata folder in workspace
MCU on Eclipse 